Background: One of the goals of new programs for silkworm breeding is to investigate the ability to withstand environmental fluctuations. Silkworms are cold-blooded organisms, meaning that their body temperature and metabolic processes are affected by the temperature of the environment. Silkworms are sensitive to temperature changes, and exposure to cold temperatures can affect their growth, development, and overall health. So far, no special attention has been paid to improving compatibility traits in Iranian silkworms. The requirement of this goal is to improve the traits related to resistance to stresses and adaptation to new conditions. Achieving this regard requires expanding the country's silkworm gene bank, especially in the field of commercial lines. New genetic resources should also be made available while identifying the genetic capabilities of the existing lines. In the meantime, producing eggs that are resistant to cold stress is one of the proposed solutions to deal with this stress. For this purpose, it is necessary to determine the level of resistance or susceptibility to cold stress in commercial lines used in the production of commercial eggs, and the desired lines should be rated from this aspect. With this rating, recommendations can be made to create crosses between the mentioned lines aiming at producing commercial eggs resistant or sensitive to cold stress and distributing each batch of these eggs in different geographical areas with different climates. In the present study, the performance of commercial lines of Iranian silkworms including 31, 32, 103, 104, 151, 153, and 154, under cold stress was investigated in control and challenge treatments. Methods: After the steps of preparation for breeding, silkworm eggs were kept in a hatching room under standard temperature and humidity conditions for 12 days. The standard conditions for breeding were temperature (25 ± 2 °C), relative humidity (75 ± 5%), and photoperiod (16 hours light/ 8 hours dark). Mulberry leaves of modified varieties were used to feed the larvae. To induce cold stress, 300 larvae on the third day of the fifth instar (in the form of three replicates of 100 larvae) were incubated at 0 °C for 12 hours and then returned to the standard rearing conditions at 25 °C. The production traits the characteristics of cocoon weight, cocoon shell weight, cocoon shell percentage, number of cocoons per liter, cocoon weight per liter, the average weight of a cocoon, the average weight of the best cocoon, the average weight of a middle cocoon, the average weight of a weak cocoon, and the average weight of a double cocoon, as well as some traits related to longevity, including the percentage of live larvae, the percentage of dead larvae, the percentage of pupal losses, and the percentage of produced butterflies, were investigated in each cold stress and control treatments. For statistical analysis, the generalized linear model (GLM) procedure was used in SAS software, and means were compared with Tukey's statistical test at a significant level of 0.05. Results: In general, the highest and lowest values of traits were not the same among the genotypes and under applied stress conditions, but some genotypes showed higher performance for a larger number of traits. Among the studied traits, those related to cocoon weight, cocoon shell weight, and cocoon shell percentage are the most important traits for breeding purposes, which have high economic values and are used to improve cocoon performance. Meanwhile, the live and dead larvae percentage traits, along with death pupae percentage and productive moth percentage, are important indicators related to viability, which showed significant differences between the studied lines. The results of mean comparisons showed that the larvae of the control group generally had better performance in all the examined traits than the larvae under cold stress, with a significant difference (P < 0.001). However, two lines 153 and 154 from the cold stress group had higher performance in many production and longevity traits than the other lines under cold stress and even some lines of the control group. Conclusion: The temperature of the breeding environment is one of the factors that, in the case of fluctuation, leads to the deviation of breeding conditions from the optimal state and damage. In general, cold stress and low temperatures have different effects on insects, considering the intensity and duration of the insect's exposure. In addition, the stage of life, the evolution degree of adaptation mechanisms, and adaptation to the environment greatly affect the insect's response to cold stress. The results of the present research show that the performance of commercial lines of Iranian silkworms is affected under cold stress conditions, and lines 153 and 154 have higher resistance than the other lines. Hence, they can be prioritized in the production of commercial hybrids in terms of resistance to cold stress and production and survival records. Further studies are suggested to measure the molecular and biochemical characteristics of some proteins related to temperature stress in different treatments. [ABSTRACT FROM AUTHOR]